Daylighting Issues Debated in IgCC Hearings

A variety of issues related to daylighting were debated in the International Code Council’s International green Construction Code (igCC) hearings, which took place last week in Memphis.

Two proposals were approved as submitted, GG260 and GG262. Their goal was to update the IgCC to be consistent with the revised 2015 IECC. GG260, section 808.2, was proposed by Thomas Culp, representing Birch Point Consulting LLC.

This proposal updates and clarifies the A-3 and B spaces required to have daylighting. The 2015 IECC requires toplighting in convention centers, and the 2012 IgCC already requires daylighting in exhibition halls. This proposal simply makes the codes consistent by adding convention centers to the list of A-3 spaces where daylighting is required, said Culp.

GG262-14, section 808.2, was proposed by Julie Ruth, JRuth Code Consulting, representing the American Architectural ManufacturersAssociation, and Culp, and was also approved. This proposal reduces the threshold size at which Occupancy Group M (retail) spaces are required to have mandatory daylighting from 10,000 square feet to 2500 square feet. The current threshold of 10,000 square feet was based upon the provisions of the 2012 IECC. This threshold size was reduced to 2500 square feet in the 2015 IECC. Energy modeling has shown that significant reduction in lighting load can be achieved for open spaces that are much smaller than the 10,000 square feet originally addressed in both the IECC and IgCC.

GG265-14 was proposed by Helen Sanders, representing SAGE Electrochromics Inc., and this proposal was ultimately not approved 11-0. Sanders proposed that Section 808.3.1.1, be revised as follows: “The daylit area shall be illuminated by fenestration that complies with Table 808.3.1.1 and Figure 808.3.1.1(4). Where fenestration is located in a wall, the daylit area shall extend laterally to the nearest 56-inch-high (1422 mm) partition, or up to 1.0

times the height from the floor to the top of fenestration facing within 45 degrees (0.785 rad) of east or west or up to 1.5 times the height from the floor to the top of all other fenestration, whichever is less, and longitudinally from the edge of the fenestration to the nearest 56-inch-high (1422 mm) partition, or up to 2 feet (610 mm), whichever is less. Where fenestration is located in a rooftop monitor, the daylit area shall extend laterally to the nearest 56-inch-high (1422 mm) partition, or up to 1.0 times the height from the floor to the bottom of the fenestration, whichever is less, and longitudinally from the edge of the fenestration to the nearest 56-inch-high (1422 mm) partition, or up to 0.25 times the height from the floor to the bottom of the fenestration, whichever is less. Vertical fenestration shall be provided with an automatically controlled method for managing glare. Such methods include automatically controlled shading devices or dynamic glazing capable of modulating in multiple steps the amount of light transmitted into the space in response to daylight levels. Control systems shall contain a manual override that shall reset to automatic control after not more than four hours. The purpose of this proposal is to add consideration of glare control to the prescriptive daylighting requirements of the IgCC.”

The proposal would have increased the cost of construction when using the prescriptive daylighting path compared to the 2012 IgCC as it now requires glare control to be addressed. The performance path for daylighting already required glare control to be included (through maximum illumination), so cost is not necessarily increased in that path – it depends on the specific method (internal or external shading, dynamic glazing, etc.).

Thom Zaremba spoke on his own behalf in opposition, saying, “the language is ambiguous” and there are needed exemptions. “What about a school on a greenfield that has trees on each side?” he asked. “What if the sun sets over the mountain on the west side?”

Tom Culp, representing the Aluminum Extruders Council (AEC), said, “We appreciate Helen bringing this forward but the language is not quite right.”

A representative from BOMA International added, “The costs of installing these automatic devices are rather large.”

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